Thorp Air Command - T18.net

Supporting Owners, Builders and Pilots of the Thorp T-18 and its variants.
It is currently Thu Sep 20, 2018 2:51 am

All times are UTC - 6 hours [ DST ]




Post new topic Reply to topic  [ 18 posts ]  Go to page 1, 2  Next
Author Message
Ryan Allen
PostPosted: Tue Dec 06, 2016 7:51 pm 
Sr. Member
Sr. Member
User avatar

Joined: Wed Oct 21, 2009 6:10 pm
Posts: 741
Images: 0
Location: Louisiana
I am considering installing a 4.5 rpm elevator trim motor in my project. Would anyone think 4.5rpm is too slow for elevator trim? I currently have the same gear motor in my flying Thorp, but it is a 17rpm motor, and sometimes I feel like I am hunting for my trim sweet spot.

Here is the one I am considering:
https://www.zoro.com/dayton-dc-gearmoto ... /G3445111/

Attachment:
4.5rpm gear motor.jpg
4.5rpm gear motor.jpg [ 14.7 KiB | Viewed 5613 times ]


Top
 Profile Personal album  
 
jrevens
PostPosted: Tue Dec 06, 2016 10:39 pm 
Sr. Member
Sr. Member
User avatar

Joined: Thu Oct 22, 2009 10:13 pm
Posts: 708
Location: USA
Others who have electric trim can answer better than I, but I suspect that it will be just fine. Better a little slow than too fast, for trim, in my opinion. It looks like a good motor, and that price is a few bucks cheaper than you can buy it direct from the supplier, W. W. Grainger (unless you have a business account at Grainger, & get a discount).

_________________
John Evens
Arvada, Colorado

T-18 N71JE (sold)
Kitfox 7 SS N27JE


Top
 Profile  
 
Rich Brazell
PostPosted: Tue Dec 06, 2016 11:17 pm 
Hero Member
Hero Member

Joined: Wed Oct 21, 2009 12:33 pm
Posts: 2875
Images: 64
Location: Jamul, CA (San Diego area)
When you say hunting for your "sweet spot" , do you mean you overshoot that magic spot ? :P It doesn't take much travel of that tab to "trim it out ." I find I just "bump" my coolie hat and it is more than enough to level things out . I have flow a lot of AC with electric trim and I find that is the case for all of them . So I would say yes...slower is better . ::) It may mean you hold the trim switch a 1/10 of a second longer , but probably less likely to overshoot . ???

RB O0


Top
 Profile Personal album  
 
jim borg
PostPosted: Wed Dec 07, 2016 12:54 am 
Newbie
Newbie

Joined: Wed Dec 07, 2011 10:18 am
Posts: 22
Images: 3
Location: MN USA
Mine turns about 11 rpm and is a little slower than I like, but is acceptable. I would think 15 to 18 would be about perfect.

Jim
N180RG


Top
 Profile Personal album  
 
Ryan Allen
PostPosted: Wed Dec 07, 2016 7:00 am 
Sr. Member
Sr. Member
User avatar

Joined: Wed Oct 21, 2009 6:10 pm
Posts: 741
Images: 0
Location: Louisiana
Yep, I feel like I am overshooting that magic trim spot with the 17rpm trim motor, but based on Jim's post, I may just stick with it for the project too.


Top
 Profile Personal album  
 
fytrplt
PostPosted: Wed Dec 07, 2016 7:26 am 
Sr. Member
Sr. Member
User avatar

Joined: Tue Oct 20, 2009 8:07 pm
Posts: 808
Images: 2
Location: Lakeland, Florida, USA
When I built my plane, I was flying the F-4 Phantom. I timed the trim system from stop to stop and found it to be 9-10 seconds. The trim screw on the T-18 turns 5 1/2 turns stop to stop. That makes for 33 RPM. I found that to be a bit fast for the T-18 in cruise, due to the sensitivity of the stab trim. The trim motor I found runs about 1/2 that, or 15-17 RPM and is just about right. I found my trim motor in a NASA junk pile at Langley AFB. Probably an actuator from a space craft. Hope it doesn't crump!

_________________
Bob Highley
N711SH
SN 835
KLAL


Top
 Profile Personal album  
 
Fraser MacPhee
PostPosted: Wed Dec 07, 2016 10:55 pm 
Sr. Member
Sr. Member

Joined: Wed Oct 21, 2009 8:57 am
Posts: 652
Images: 19
Location: USA
FWIW, my trim is 12 seconds stop to stop, which is about 27-28 RPM......I find it OK - that sweet spot is pretty narrow, and for those of us with just a header tank, it never lasts very long.

_________________
Fraser MacPhee
N926WM
Serial #279-1
Draper, UT


Top
 Profile Personal album  
 
Rich Brazell
PostPosted: Thu Dec 08, 2016 12:06 am 
Hero Member
Hero Member

Joined: Wed Oct 21, 2009 12:33 pm
Posts: 2875
Images: 64
Location: Jamul, CA (San Diego area)
Bob...did they have any $600 toilet seats or $400 hammers in that NASA junk pile ? :o

RB O0


Top
 Profile Personal album  
 
stevehawley
PostPosted: Thu Dec 08, 2016 6:02 am 
Jr. Member
Jr. Member

Joined: Tue Mar 02, 2010 2:30 pm
Posts: 78
Location: USA
A trip down memory lane: back in 1980 I had bee flying my T-18 for a little while when I got a call from Leroy Holt in McAlester, OK. He was getting close to finishing his and ask me to fly down and look it over and perhaps answer a few questions. I flew down and he picked me up and we went out to his shop. His project was coming right along and we had a good discussion and got to know one another a little. I noticed on his work bench a little "gear box" about the size of a regular pack of cigarettes. The workmanship on it was out of this world! The input shaft had what appeared to be jeweled bearings similar to a Swiss watch, same with the output shaft. I asked him what it was for and he said the little automobile window operating moter for his electric trim was to fast so this gear box was to be a speed reducer. I asked him what it was made for and where he found it. He worked in the US Naval Arsenal near McAlester and he found it in a junk pile there much like Col. Bob did his. It was part of the arming mechanism from a Mark 4 atom bomb!!!
Steve Hawley


Top
 Profile  
 
Binder
PostPosted: Sun Dec 25, 2016 4:28 pm 
Sr. Member
Sr. Member

Joined: Thu Sep 01, 2016 10:50 pm
Posts: 220
I haven't had mine open to examine mine but I will next fall at annual. I actually do not like electric trim. I like to feel the wheel and not have one more electrical component and gear connections to service and wear out.

Mine is way too slow. I often have to hold the button for a few seconds when trimming for pattern altitude and decent base to final. It's quite annoying. When I decide what I'm going to build it will most likely have manual trim.

I'm used to electric flaps in the Cessna planes although I prefer my manual flaps in the thorp. I've oddly had many motor and switch failures through the years on flap motors.


Top
 Profile  
 
jrevens
PostPosted: Mon Dec 26, 2016 11:57 am 
Sr. Member
Sr. Member
User avatar

Joined: Thu Oct 22, 2009 10:13 pm
Posts: 708
Location: USA
Binder wrote:
I haven't had mine open to examine mine but I will next fall at annual. I actually do not like electric trim. I like to feel the wheel and not have one more electrical component and gear connections to service and wear out.

Mine is way too slow. I often have to hold the button for a few seconds when trimming for pattern altitude and decent base to final. It's quite annoying. When I decide what I'm going to build it will most likely have manual trim.

I'm used to electric flaps in the Cessna planes although I prefer my manual flaps in the thorp. I've oddly had many motor and switch failures through the years on flap motors.


I'm with you, Jeff.

_________________
John Evens
Arvada, Colorado

T-18 N71JE (sold)
Kitfox 7 SS N27JE


Top
 Profile  
 
Binder
PostPosted: Wed Mar 01, 2017 11:23 pm 
Sr. Member
Sr. Member

Joined: Thu Sep 01, 2016 10:50 pm
Posts: 220
well my electric trim motor failed.

I'm starting another thread but I figured I would ask here. Does anyone know where this motor is mounted in the plane?


Top
 Profile  
 
Ryan Allen
PostPosted: Thu Mar 02, 2017 6:10 am 
Sr. Member
Sr. Member
User avatar

Joined: Wed Oct 21, 2009 6:10 pm
Posts: 741
Images: 0
Location: Louisiana
Here you go......
viewtopic.php?f=4&t=6201&hilit=trim+motor+grainger&start=0


Top
 Profile Personal album  
 
Fraser MacPhee
PostPosted: Fri Mar 03, 2017 11:22 am 
Sr. Member
Sr. Member

Joined: Wed Oct 21, 2009 8:57 am
Posts: 652
Images: 19
Location: USA
Jeff - I used to have a T-18 where the trim motor was mounted just aft of the baggage compartment under the deck, with a long aluminum tube to the jack screw. The advantage to that was that if the motor went T-UP, you didn't have to pull the tail to replace it. Having said that, the tail is easy to remove (mind your torque when re-installing the bolts) and I think that the installation referenced above is superior to the one I had.

_________________
Fraser MacPhee
N926WM
Serial #279-1
Draper, UT


Top
 Profile Personal album  
 
Binder
PostPosted: Sun Mar 05, 2017 9:23 am 
Sr. Member
Sr. Member

Joined: Thu Sep 01, 2016 10:50 pm
Posts: 220
Thank you both!

Seems like each time I visit the hanger during this "minor" upgrade I'm finding many deficiencies with the airplane that need fixed to my liking. I appreciate all the amazing help from you guys here.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 18 posts ]  Go to page 1, 2  Next

All times are UTC - 6 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
cron

[ Time : 0.094s | 12 Queries | GZIP : On ]